1. Field of the Invention
The present invention relates to a rotary gas treating apparatus, and more particularly to a gas treating apparatus of this type including a front-stage rotor and a rear-stage rotor each consisting essentially of an adsorbent material and allowing gas flow along a rotational axis, the rotor having, within respective rotational areas thereof, adsorbing areas for introducing a treatment-object gas and desorbing areas for introducing a recycling gas; the adsorbing area of the front-stage rotor and the adsorbing area of the rear-stage rotor being disposed in the mentioned order in a continuous treatment-object gas flow passage from an upstream side thereof; the desorbing area of the front-stage rotor and the desorbing area of the rear-stage rotor being disposed in recycling gas flow passages, respectively. In operation, the apparatus continuously treats the treatment-object gas through adsorption and desorption repeated by way of revolutions of the front-stage rotor and the rear-stage rotor through the adsorbing areas and the desorbing areas thereof.
2. Description of the Related Art
Conventionally, in a rotary gas treating apparatus of the above-described type, the front-stage rotor and the rear-stage rotor are revolved in the same direction (e.g. a Japanese laid-open utility model gazette No. 55-144526).
However, through study of adsorbing effect of the rotor on adsorbed matter to be eliminated from the treatment-object gas, the following findings have resulted. Namely, an accumulation amount of adsorbed matter in the rotor is smaller on the upstream side of the revolving direction of the rotor (to be referred to briefly as the revolving direction, hereinafter) because of a short passage time period of the matter through the adsorbing area at this upstream side. Whereas, the accumulation amount in the adsorbing area gradually increases up to a saturation point towards the downstream side of the revolving direction.
As a result, the adsorbing effect on the matter in the treatment-object gas decreases on the downstream side of the adsorbing area relative to the revolving direction.
On the other hand, as to the relationship between the front-stage rotor and the rear-stage rotor, because of the above-described, decreasing adsorbing effect on the downstream side of the adsorbing area in the revolving direction, an amount of the matter which escapes through the front-stage rotor without being adsorbed thereby gradually increases on the downstream side of the adsorbing area of this front-stage rotor. Therefore, there occurs high concentration of the matter in its distribution after the gas passage through the adsorbing area of the front-stage rotor.
Then, partly because the distance between the front-stage rotor and the rear-stage rotor is rather limited, the treatment-object gas having the above-described matter concentration distribution after its passage through the adsorbing area of the front-stage rotor tends to reach the adsorbing area of the rear-stage rotor with the gas generally maintaining the uneven matter concentration distribution.
However, with the conventional apparatus, the front-stage rotor and the rear-stage rotor are rotated in the same direction. Therefore, in the adsorbing area of the rear-stage rotor, because of the above-described revolving direction, there occurs disadvantageous matching between a direction in which the matter concentration increases because of the uneven distribution and a further direction in which the adsorbing effect of this rear-stage rotor gradually decreases because of the gradual increase in the matter accumulation amount. As a result, on the upstream side of the adsorbing area of the rear-stage rotor, there occurs insufficient utilization of the adsorbing effect because the matter concentration in the gas reaching this side is low in spite of the relatively high adsorbing capacity at this portion. On the other hand, on the downstream side of the adsorbing area of the rear-stage rotor, the treatment gas containing a great amount of the matter reaches this portion where its adsorbing capacity is relatively low. Accordingly, even if this portion has enough capacity for adsorbing the entire amount of the matter, or if the total amount does not exceed the saturation point, because the adsorbing effect is relatively decreased, a significant amount of the matter will escape through the rear-stage rotor without being trapped therein. Consequently, the treatment performance of the entire apparatus suffers.
One conceivable method to restrict the above-described deterioration in the treatment performance is to increase the thickness of each rotor in the rotational axis direction (i.e. the passage direction of the treatment-object gas). However, this invites physical enlargement of the apparatus, increases of energy consumption and of apparatus costs.
The object of the present invention is to enhance the treatment performance of the apparatus through rational improvement thereof without inviting the problems such as the enlargement of the apparatus, increases of the energy consumption and of the apparatus costs.